Cellobiose, 1—»4-/3-link

Cellulose consists of several thousand o-glucose units linked by l- 4-/3-glyco-side bonds like those in cellobiose. Different cellulose molecules then interact to form a large aggregate structure held together by hydrogen bonds. 

Similarly, per-O-trimethylsilylated mono- and P-linked disaccharides (lactose and cellobiose, not melibiose) could be converted into the corresponding a-glycosyl iodides, which upon SN2 displacement with CbT using TBACN mainly afforded P-cyano derivatives in good overall yields [191]. The cyanoglycosides were transformed into aminomethyl glycosides via reduction under mild conditions (Scheme 2.52). 

Configurational dependence of lJc-, c-v> values has been observed with acetates of [l -13C]-labelled cellobiose, laminarabiose, maltose, and nigerose, the a- and /3-linked disaccharides respectively giving29 the values of 46.5 and 49.2 Hz. 

The pendant hydroxyl groups of cellobiose have been confirmed to be useful for crosslinking of its polymers in the presence of additional amount of diisocyanate. Cross-linked insoluble films have been obtained by casting a polymer solution in dimethylacetamide containing 7% of additional amount of MDI. 

D-glucose in the ratio of 8.3 1 and only a trace of a di-O-methyl-D-glucose, further confirming that it was a (1—>6)-linked polymer. The disaccharide fraction from the zinc chloride polymerization of 1,3,4,6-tetra-O-acetyl-D-glucose gave sophorose and kojibiose in the ratio of 3 1, whereas 1,2,3,6-tetra-O-acetyl-D-glucose gave cellobiose and maltose in the same ratio. 

Cellobiose, a dimer of /3-1,4-linked glucose, is reported to be a cellulase inducer in T. reesei as well as in several other fungi (20,28,33, 34). But whether cellobiose is a true inducer is questionable since Reese et al. (35) reported that cellobiose could induce as well as inhibit cellulase biosynthesis. The same is also true for glucose. Whether glucose or cellobiose is an inducer or inhibitor depends on the concentration of sugars in the environment. 

Two sugars can link to each other by losing water from OHs to form disaccharides. Figure 4.6 shows the Haworth projection formulas of four important disaccharides sucrose, lactose, maltose, and cellobiose, which all have the same molecular formulas, C12H22011. Sucrose and lactose are the most abundant and most important disaccharides of natural origin. Maltose and cellobiose are repeating units of polymeric starch and cellulose, respectively. Disaccharides may hydrolyze to form two monosaccharide molecules. 

---